At present, a 3GPP LTE-A system has agreed to use a carrier aggregation technology as a method for extending a system bandwidth, so as to support a peak data rate of up to 1 Gbps. The main idea of carrier aggregation is to aggregate multiple component carriers into a large-bandwidth carrier so as to support a high data rate.
A user equipment (User Equipment, UE) may aggregate carriers from two different stations, so as to implement carrier aggregation between different stations. For example, when a UE is located at a cell edge, the UE may aggregate low-band carriers from a macro base station and high-band carriers from a relay station (Relay Node, RN).
When the UE uses carriers from different stations, the UE and a radio network may maintain a radio resource control (RRC) connection therebetween, or may maintain multiple radio resource connections therebetween. As described in the above example, the UE is served by the macro base station and the RN, and has established a data connection with both the macro base station and the RN, but the UE may maintain an RRC connection with only one of the macro base station and the RN, or may maintain two RRC connections with both the macro base station and the RN.
In the case of carrier aggregation between different stations, if a UE that is using the carrier aggregation technology or is ready to use the carrier aggregation technology needs to be handed over, there is no related technical solution that can solve the problem about how to hand over the UE. That is, firstly, when the UE is served by multiple stations based on the carrier aggregation technology, if the UE needs to be handed over, the UE cannot be handed over quickly and the current service of the UE cannot be recovered quickly according to the related technology; secondly, no matter whether the UE is using the carrier aggregation technology, if the UE expects to use the carrier aggregation technology after the handover, the UE cannot be directly handed over to two stations and the current service of the UE cannot be recovered quickly according to the related technology.
Therefore, before or after a UE handover, if the UE needs to use the carrier aggregation technology, how to quickly hand over the UE and quickly recover the current service of the UE for improving user experience is a problem that needs to be solved urgently.